[whatsnewell]

It would seem to me that if the light is "on" (reverse polarity) it means either the wiring in your power cord plug (male) is reversed, or the wiring in the 50 amp electrical receptacle (female) is reversed. It would be a warning (if lit) that something is wrong with the electrical receptacle you have plugged into, assuming it has not been coming on every time you have plugged in before.